1. Field of the Invention
This invention relates to a method of transmitting information over the radio frequency spectrum, generally on a one way basis, which materially improves the efficiency of such transmission.
2. Brief Description of the Prior Art
The radio frequency (RF) spectrum is known to be finite. Accordingly, with the increasingly greater use of radio frequencies and equipment requiring the use of radio frequencies, the availability of such frequencies at any particular point in time becomes increasingly problematical. Accordingly, in some geographical areas, access at any particular time to radio frequencies for information transmission may not be and presently often is not available when requested. In fact, it is well known that only a small fraction of the total population of large cities can be accommodated with cellular telephone technology, this being an example of this problem. It is therefore apparent that there is a present need to adopt improved technology and/or the improved and more efficient use of the present technology to ameliorate this problem.
One level of communication technology which utilizes the radio frequency spectrum is the pager technology and particularly the portion of this technology which operates on a send only basis, this being communication which operates mainly in one direction. At present, even this technology is subject to the above described problem of radio frequency access since it operates in the same frequency ranges as do other technologies. A problem generally inherent in all of the present technologies which transmit via radio frequencies is that the data being transmitted, whether analog or digital, is generally transmitted at the speed at which it was originally created including pauses between periods of data creation or xe2x80x9cdead timexe2x80x9d. This causes a utilization of the radio frequency during access for a greater period of time than may be necessary to adequately transmit the data as well as utilization during periods of non-use.
In accordance with the present invention, the above described problem inherent in the present prior art is minimized and there is provided a method of transmission of data, generally in one direction, for use in conjunction with pager-type equipment, which materially decreases the time required for transmission of such data.
Briefly, in accordance with the present invention, there is provided a wireless communication system in which a brief message, which can be an analog message, such as an audible message, or a digital message, such as an audible message which has been converted to digital code or an originally created digital message, is stored at the transmitter, time-compressed, generally with but not limited to a digital signal processor (DSP) and transmitted when radio frequency spectrum space is available as a brief burst of transmission requiring far less transmission time than would be required for creation of the original data due to the data time-compression. In a typical operation, the user will dial the number of the station which is to receive the message and then create the message in a telephone, such as a cellular telephone. The telephone will include circuitry which compresses and stores the number of the station being called and the message created, whether analog, analog converted to digital or digital, and transmits the compressed message to a predetermined central station (as is the case of all cellular telephones) as soon as RF spectrum space is available. In the event the telephone is not equipped to time-compress the data, the data can be transmitted in uncompressed form to a central station and time-compressed at the central station. It is understood that there are generally a plurality of spaced apart central stations, each capable of receiving from and transmitting to and from the telephones as well as to and from other central stations. When there are plural central stations in use, generally all of the central stations are capable of receiving and transmitting concurrently to and from each telephone as well as to and from each other in order to be able to locate the receiver telephone anywhere within the total area being covered by the system. This is accomplished by standard repetitive redial in the event space is initially not available. The time-compressed message and address of the station to receive the message, when received, is stored at the central station and optionally provides an answer back to the transmitting station indicating that the message has been received and stored at the central station. The central station then transmits the time-compressed message to the station to receive the message by dialing the stored address of the receiving station as soon as radio frequency spectrum is available, using the redial as discussed above if space is initially not available, and can optionally receive an answer back from the receiving station to indicate that the message has been received at the receiving station. The receiving station time-decompresses and stores the original message for replay and notifies the user at the receiving station that a message has been stored by conventional procedures, such as, for example, a ring, beep, vibration, etc. The receiving user can then play the message when convenient. The receiving station can be another cellular telephone or a telephone connected to regular telephone lines with the ability to time-decompress and store as noted above with regard to the cellular telephone receiving station.
As a further embodiment, the data, whether analog (audio) or digital (analog converted to digital or original digital) can be transmitted via a PC through the internet to an E-mail address using the above described concepts.
It can be seen that the time period during which the radio frequency spectrum is utilized is greatly reduced due to the time-compression and time-decompression of the message and can be limited to the time required to transmit the highly time-compressed message alone with avoidance of the dead time. It is noted that the terms xe2x80x9ctime-compressionxe2x80x9d and xe2x80x9ctime-decompressionxe2x80x9d relate to the time required to send a message and that these terms are in no way related to the use of algorithms and processing used to minimize the number of bits required to adequately represent speech which is another form of data compression.
While the above description relates specifically to cellular type telephones which have been additionally fitted with a DSP or other type of device capable of performing the above described functions, it should be understood that standard type telephones can also be provided with the above described capability by calling via standard telephone lines to a specially provided service number, preferably at the cellular telephone central station, which telephone has the capability of performing the functions of the DSP or other type of device and proceeding as described above. Such operation still saves radio frequency spectrum time for telephone calls from a telephone which uses the regular telephone lines to a cellular type telephone which uses radio frequencies as a means of transmission and reception of information.